it sounds like the cam is not installed right and your timing may show to be right but its actually off.
rbohm said:cam timing and compression sound like they are incompatible. you gave some specs for the cam, but what is needed is the valve overlap spec. if it is low(below 30 degrees) then you should be ok as it will add dynamic compression. if it is high(above60 degrees) then you lose dynamic compression. for a low compression engine you need low overlap, and it sounds like you have high overlap, and low compression.
also who's cam did you buy? i usually recomend something like the he260h, or the he268h from comp cams, or the performer or performer rpm cams from edebrock. these cams are designed for low end and mid range performance and are perfect for the daily driver.
ratio411 said:That is the classic description of "RV" cam.
When folks use the term RV, it means more recreational car, cruiser, nice pick-up, sunday driver... etc.
A smooth cam that makes plenty of torque to move your ride and get you stoplight to stoplight without revving to the moon.
That sounds like a nice street cam. Cams like this are designed to make more vacuum and cylinder pressure. This allows you to run your power accessories and use streetable static compression.
Things that help you with you "recreational" driving.
Dave
crushnut said:Im an idiotWhat are you talking about?
ratio411 said:Edit:
Forget it...
I haven't looked into an AFB for 10+ years...
Dave
ok to determine you valve overlap, the time at which both valves are open at the same time, you will use the sae timing numbers as in this case they are more accurate. take the number at which the intake valve opens, and add the number at which the exhaust valve closes, which in this case the intake opens at 27 btdc, and the exhaust closes at 34 atdc. adding them together gets you 27+34=61 degrees of valve overlap. thids means that this cam was designed to work with an engine that has a compression ratio of 9.5-10.5:1 so you can lower the dynamic compression ratio at low to moderate speeds to reduce or eliminate detonation, while keeping good overall engine power. since it sounds like your compression ratio is much lower, likely closer to 8.0-8.5:1 you need a cam with a shorter overlap period. and lest anyone question why you use the sae(advertised) timing numbers over the .050 timing numbers, remember that when the intake valve opens there is still positive pressure in the cylinder, and this pressure along with piston movement is what is used to bleed off cylinder pressure to lower the dynamic compression pressure at low speeds. at high speed this makes no real difference as everything is moving too quickly for it to.crushnut said:Can you elaborate more on the valve overlap spec. that you were talking about please? The only other specs on the cam card are SAE timing and .050 timing.
SAE Timing- BTDC 27, ABDC 73, BBDC 75, ATDC 34
.050 Timing- BTDC -6, ABDC 30, BBDC 43, ATDC -9
D.Hearne said:Crushnut------- what brand & part # pistons did you use ? What is their pin height ( compression height or distance from the pin center to the top of the piston) Do they have two or four valve reliefs? Did you happen to measure how far down the bore they are at TDC? What head gaskets did you use ? Were your rods reconditioned? All these questions need to be answered to accurately determine the comp ratio. Not all flat top 302 pistons actually place the piston tops at or near the block's deck surface. Many so called flat tops end up with a -.020-.040 deck clearance.This makes a huge difference in the comp ratio on a smalll displacement motor like a 289 or 302 Also depends on what year block you have too as the others have mentioned.
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